Because life expectancy is increasing in the United States, The number of persons aged sixty-five or older will be more than that of persons aged nineteen years or younger by mid-1990's. It is well recognized that. as persons grow older, the incidence of root surface caries increases. Less well recognized however. is the observation that the output of the submandibular and sublingual glands declines with age. This phenomenon may be further complicated by the extensive use of prescription drugs that have a hyposalivatory effect. It is estimated that 75% of the population aged 65 or older take one or more prescription drugs with a hyposalivatory effect. The effect that age and/or drugs have on composition of saliva and in particular the submandibular and sublingual saliva remains largely unexplored. The influence of chronic ingestion of hyposalivator drugs on coronal and root surface caries development has not been examined eve though it is recognized that a major reduction in the total volume of saliva lead to enhanced levels of caries. In the proposed studies. we will examine the influence of administration of the commonly prescribed atropine (cholinergic antagonist). propranolol (beta adrenergic antagonist), and amitriptyline (cholinergic and alpha adrenergic inhibitor) administered by means of osmotic pumps on caries development, salivary output, and composition of saliva in rats of various ages. We will also explore the effects of these regimens on the microbial flora of the mouth. In addition, the ability of saliva collected from ducts and particular salivary constituents to bind to HA and the ability of microorganisms to bind to HA will be explored. The results of these studies will help to clarify the influence of drugs on salivary gland physiology and biochemistry and caries development. They will also aid in identifying particular constituents in salivassociated with caries resistance and help to classify groups of drugs which may enhance particularly caries promoting because of their effect on the composition of saliva. Equally, the study could lead to the development of a drug-that may enhance the level of caries protection exerted by saliva.